1. Field
An aspect of embodiments of the present invention relates to a pixel and an organic light emitting display device using the same.
2. Description of Related Art
Flat panel display devices with reduced weight and volume in comparison to a cathode ray tube have been developed. The flat panel display devices include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), and an organic light emitting display.
The organic light emitting display displays an image by using organic light emitting diodes which emit light when electrons and holes are re-combined, and has a rapid response and a low power consumption.
The organic light emitting display device includes a plurality of pixel arranged at crossings between a plurality of data lines, a plurality of scan lines, and power lines in a matrix form. Each of the pixels includes an organic light emitting diode, a driving transistor for controlling a current flowing through the organic light emitting diode, a storage capacitor for storing a voltage corresponding to a data signal, and a compensation circuit for compensating a threshold voltage of the driving transistor.
The pixel stores a voltage corresponding to the threshold voltage and the data signal of the driving transistor to the storage capacitor and supplies a current corresponding to the stored voltage to the organic light emitting diode to display an image.
In order to display an image at a desired gray level, voltages respectively charged at the storage capacitors of the pixels must be kept uniform. Therefore, four or more transistors are connected to a current leakage path to prevent a voltage of the storage capacitor from being changed.
For example, in the case where a first transistor is formed on a first current leakage path connected to the storage capacitor and a second transistor is formed on a second current leakage path, each of the first transistor and the second transistor is formed by connecting at least four transistors in series. However, although the at least four transistors are connected on the current leakage path as described above, a leakage current of a certain amount is generated so that an image of a desired brightness or gray level cannot be displayed. In addition, according to the conventional art, a storage capacitor is formed to have a large capacity in order to cope with the leakage current, and therefore, aperture ratio of the display device is lowered.